In a medium bowl, sift together flour, baking soda, salt and spices. Set aside. In a large bowl, by hand (or with an electric mixer), cream the butter until it is light and fluffy. Add the sugar and mix again until light and creamy. Blend in the eggs one at a time and then the molasses. Add the flour mixture in two additions either by hand or on low speed. The dough should be easy to handle, and not overly tacky. If needed, add more flour, one tablespoon at a time, until it isn't overly sticky. Divide the dough into two pieces, wrap each in plastic and chill for an hour or so. Heat oven to 350 degrees, racks in the middle, and line a couple baking sheets with parchment paper. Set aside.
Roll the dough out onto a lightly floured countertop roughly 1/8-inch thick and cut into gingerbread cookie shapes. Transfer to baking sheets. Bake for 7 -10 minutes (for 3 - 4-inch cookies), less for smaller cookies, more for larger. Allow to cool completely before icing.
Whisk together the powdered sugar and egg white until smooth and silky. It takes a few minutes. Reserve a bit of this mixture if you like a more opaque icing. You can thin with water from here (one teaspoon at a time) depending on your preference. You can also add any coloring you like at this point. Use a brush (or piping bag) to paint the icing on the cookies, allow to dry completely, store in an airtight container for up to a week.
Makes about 3 dozen four-inch gingerbread men.